Recently, a semiconductor laser device has progressed in miniaturization, lightening, high reliance and high output and, thus, is utilized as a light source for personal computers, electronic equipment such as DVD, processing equipment and optical fiber communication. Inter alia, a nitride semiconductor (InxAlyGa1-x-yN, O≦x, 0≦y, x+y≦1) attracts attention as a semiconductor laser device which can emit from a relatively short wavelength ultraviolet region to a red color.
In such the semiconductor laser device, a buffer layer, an n-type contact layer, a crack-preventing layer, an n-type cladding layer, an n-type light-guiding layer, an active layer, p-type cap layer, a p-type light-guiding layer, a p-type cladding layer and a p-type contact layer are formed in this order on a sapphire substrate. In addition, a stripe-like emitting layer is formed by etching or the like and, then, a p-side electrode and an n-side electrode are formed. Further, after a light emitting plane is formed at a prescribed resonator length, a mirror plane on a light reflecting side is formed, whereby, the oscillated light can be effectively taken out through the mirror plane.
However, in such the structure, there is a problem that irregularity (ripple) is generated in far field pattern (FFP), leading to a non-Gaussian distribution. In a semiconductor laser device in which FFP has a non-Gaussian distribution, there is also a problem that calculation of a shape of FFP makes a great error, and connection to an optical system can not be realized effectively and, for this reason, a driving current becomes great.
In addition, in the previous semiconductor laser device, there is a problem that an emitting end is easily deteriorated.
Then, the first object of the present invention is to provide a semiconductor laser device which has no ripple and can afford better FFP having a pattern near a Gaussian distribution upon operation at the high output.
In addition, the second object of the present invention is to provide a semiconductor laser device which can prevent an end from deteriorating and afford better FFP even when operated at the high output.